Wavelength Of Optical Radiation Research Articles

The influence of temperature on spectral characteristics of silicon photovoltaic cells

The influence of temperature on spectral characteristics of silicon photovoltaic cells

Fiber-Optic Sensor for Identifying Liquids and Determining Solutions Concentration

Fiber-optic sensors for identifying liquids and determining the concentration of solutions have been studied with the possibility of using various types of single-mode optical fibers produced by industry and widely used in optical cables and telecommunications to create sensors for identifying liquids and determining the concentration of solutions. To identify liquids with different refractive indices and determine the concentration of substances dissolved in water, the peak value of the reflectograms of the optical fiber located at the interface between the optical fiber core and the environment can be used as an information parameter. The value of the information parameter depends on the refractive index of the liquid in which one end of the optical fiber is located. The parameters of fiber-optic sensors for identifying liquids and determining the concentration of solutions were studied by optical reflectometry in different wavelength ranges of optical radiation with a duration of reflectometer probe pulses from 25 to 300 ns. It has been established that the fiber-optic sensor can operate at any wavelength of optical radiation corresponding to the transparency windows of the optical loss spectrum of the optical fiber. The influence of the length of the optical fiber between the recording device and the place where the concentration of a liquid solution is determined using a fiber-optic sensor was studied. The possibility of creating a fiber-optic sensor for determining the concentration of the liquid solutions based on optical fibers has been demonstrated.

Detection of the Information Leakage Channel from Multimode Optical Fiber Using a Silicone Photomultiplier

Currently, fiber-optic communication lines are widely used for data transmission. Despite the fact that the information signal propagates inside the optical fiber, covered with a protective shell, there are various ways to form information leakage channels from such fibers. The power control of the information signals transmitted over an optical fiber is one of the most common ways to detect an information leakage channel. This paper determines the parameters of a fiber-optic communication line based on multimode optical fibers for which silicon photomultipliers to detect information leakage channels can be used. The dependences of the branched power on the fiber bending diameter are presented. It has been found that the bending diameter increase leads to the branched power decrease and a decrease in the ability of the photodetector to detect power loss in the optical fiber. The value of the branched power of optical radiation with a wavelength of 850 nm is greater than for 650 nm for all studied bending diameters. It has been established that an increase in the optical radiation power introduced into the fiber to 10 mW makes it possible to detect power loss up to –0.005 dB for an optical radiation wavelength of 850 nm, and –0.142 dB for a wavelength of 650 nm. The results of this article can be used in systems for protecting information transmitted over fiber-optic communication lines.

Study of the characteristics of germanium avalanche photodiodes in the photon counting mode

A study was made of the characteristics of photodetectors for fiber-optic communication lines using quantum cryptographic systems – germanium avalanche photodiodes operating in the photon counting mode. In particular, it was established at what highest temperature the implementation of the photon counting mode is possible, and the influence of temperature and overvoltage on the sensitivity of photodiodes is also considered. An experimental setup has been developed for the research. It has been determined that the highest ambient temperature at which LFD-2 germanium avalanche photodiodes operate in the photon counting mode is 243 K. It has also been found that the highest sensitivity of germanium avalanche photodiodes corresponds to the optical radiation wavelength range of 1310÷1490 nm. Lowering the temperature leads to an increase in the sensitivity of germanium avalanche photodiodes. It was found that the dependence of the signal-to-noise ratio on overvoltage has a maximum corresponding to overvoltage ΔU = 0.1 V. Lowering the temperature led to an increase in sensitivity and signal-to-noise ratio. Since there was no shift in the maximum dependence of the signal-to-noise ratio on the overvoltage, it was therefore concluded that when the avalanche photodiode operates in the photon counting mode, in order to ensure maximum sensitivity, it is necessary to select the overvoltage corresponding to the maximum signal-to-noise ratio. The results obtained can be used in quantum cryptographic systems, technical means of protecting information transmitted over fiber-optic communication lines, and for the metrology of single-photon radiation sources.

Acoustic and acousto-optic properties of Ge-=SUB=-a-=/SUB=-Se-=SUB=-b-=/SUB=-Te-=SUB=-c-=/SUB=- and Si-=SUB=-a-=/SUB=-Se-=SUB=-b-=/SUB=-Te-=SUB=-c-=/SUB=- glasses in case diffraction on longitudinal and shear acoustic waves

We investigated acoustic and acousto-optic properties of glasses based on germanium, selenium, silicon and tellurium. The results of measurement are presented for two group of glasses including germanium, selenium and tellurium (GeSeTe) and silicon and tellurium (SiTe). The major characteristics of glasses such as the velocity of longitudinal and shear acoustic waves as well as the values of figure of merit are presented. The values of figure of merit are obtained by diffraction on longitudinal and shear acoustic waves at the wavelength of optical radiation λ = 3.39 μm. We also present the results of measurements of acoustic attenuation values α for longitudinal and shear acoustic waves in tellurium glasses at ultrasound frequencies in the range f = 75-100 MHz. Keywords: acousto-optics, acousto-optic figure of merit, germanium, selenium, silicon, tellurium, attenuation acoustic waves.

Investigation of the characteristics of matrix multi-element avalanche photodetectors operating in the photon counting mode

At present, matrix multi-element avalanche photodetectors operating in the photon counting mode are widely used for detecting optical radiation. However, the char-acteristics of matrix multi-element avalanche photodetectors operating in this mode are currently insufficiently studied. Prototypes of Si-photomultiplier tubes (Si-PMTs) with a p+–p–n+ structure produced by JSC Integral (Republic of Belarus), as well as serially produced silicon photomultipliers Ketek PM 3325 and ON Semi FC 30035 have been used as objects of research. This article presents the research results of characteristics in the photon counting mode of the specified photodetec-tors. The dependences of the specific amplitude sensitivity ratio on the wavelength of optical radiation, the temperature, the supply voltage of the matrix multi-element avalanche photodetector are determined.

Two-dimensional image edge enhancement using a spatial frequency filter of two-color radiation

Two-dimensional optical image edge enhancement is investigated using a spatial acousto-optical (AO) filter operating at two wavelengths of optical radiation, which significantly increases the reliability of measurements and also reduces the effect of noise. The filter operates basing on diffraction of light in two diffraction orders. It is shown that, in the general case, it is impossible to obtain a two-dimensional image contour simultaneously at two wavelengths at the same energy and frequency-angular parameters of the AO filter. A regime has been found that makes it possible to switch from one wavelength to another while maintaining the operation of edge enhancement by changing the acoustic power. This regime has been experimentally confirmed by the example of the formation of a two-dimensional image contour using two-colour radiation of an Ar laser emitting at wavelengths of 0.488 × 10−4 and 0.514 × 10−4 cm, and an AO cell made of TeO2, operating at a sound frequency of 57 MHz.

Turning Carbon Dioxide and Ethane into Ethanol by Solar-Driven Heterogeneous Photocatalysis over RuO2- and NiO-co-Doped SrTiO3

The current work focused on the sunlight-driven thermo-photocatalytic reduction of carbon dioxide (CO2), the primary greenhouse gas, by ethane (C2H6), the second most abundant element in shale gas, aiming at the generation of ethanol (EtOH), a renewable fuel. To promote this process, a hybrid catalyst was prepared and properly characterized, comprising of strontium titanate (SrTiO3) co-doped with ruthenium oxide (RuO2) and nickel oxide (NiO). The photocatalytic activity towards EtOH production was assessed in batch-mode and at gas-phase, under the influence of different conditions: (i) dopant loading; (ii) temperature; (iii) optical radiation wavelength; (vi) consecutive uses; and (v) electron scavenger addition. From the results here obtained, it was found that: (i) the functionalization of the SrTiO3 with RuO2 and NiO allows the visible light harvest and narrows the band gap energy (ca. 14–20%); (ii) the selectivity towards EtOH depends on the presence of Ni and irradiation; (iii) the catalyst photoresponse is mainly due to the visible photons; (iv) the photocatalyst loses > 50% efficiency right after the 2nd use; (v) the reaction mechanism is based on the photogenerated electron-hole pair charge separation; and (vi) a maximum yield of 64 μmol EtOH gcat−1 was obtained after 45-min (85 μmol EtOH gcat−1 h−1) of simulated solar irradiation (1000 W m−2) at 200 °C, using 0.4 g L−1 of SrTiO3:RuO2:NiO (0.8 wt.% Ru) with [CO2]:[C2H6] and [Ru]:[Ni] molar ratios of 1:3 and 1:1, respectively. Notwithstanding, despite its exploratory nature, this study offers an alternative route to solar fuels’ synthesis from the underutilized C2H6 and CO2.

Research of multisensor characteristics based on optical fiber

The research results of multisensors based on optical fiber, the principle of which is to change the conditions of propagation of optical radiation in the optical fiber in the places where macro-bends are formed at the points of impact, are presented in the paper. The formation of macro-bends leads to an additional attenuation of the power of optical radiation propagating through the optical fiber. A single-mode optical fiber was used with the parameters, which are supported by numerous manufacturers and comply with the recommendations of ITU-T G.655. The measurements were carried out for four wavelengths of optical radiation (1310, 1490, 1550, 1625 nm), corresponding to the transparency windows of the optical loss spectrum of the optical fiber. Using optical reflectometry methods, it was determined that the amount of attenuation of optical radiation of each macro-bend formed at the point of action of the multisensor does not depend on the number of simultaneously formed macro-bends and also does not depend on the location of the point of action along the length of the multisensor. The dependences of the attenuation of the optical radiation power introduced by the macro-bends of the optical fiber on the radius, length, or angle of the macro-bends formed at the multisensory impact points are determined experimentally. The obtained dependences also allow one to determine the optimal parameters of the formed macro-bends of the multisensor to obtain the maximum range of attenuation change for each value of the wavelength. The values of the minimum distance between the impact points, the maximum number of impact points and the optimal values of the radius and angle of the optical fiber macro-bend at the impact points are determined. The results obtained provide opportunities to continue the development of multisensors that allow us to receive information about parameters from several impact points, that are located on a single optical fiber, simultaneously.

Experimental studies to identify the influence of low power monochromatic optical radiation on the seeding qualities of cucumber seeds variety “Feniks+”

A further increase in the volume of cultivated and harvested agricultural products today depends not on the expansion of sown areas, but on scientific achievements aimed at increasing yields. The experimental study presents the results of studying the effect of low-power monochromatic optical radiation on the seeds of cucumbers of the “Fenisk+” variety. The research is based on the principles of refusal to use chemical fertilizers, the use of natural organic substances, and the creation of conditions for the growth and development of plants, identical to the conditions of their natural growth. There are various physical effects, including those based on the use of electrical energy and its transformation into light energy. Monochromatic optical radiation can be attributed to such effects. Based on the analysis of the experimental results, regression equations were obtained for the dependence of the average dry weight of cucumber seedlings on the wavelength of irradiation and exposure, and the optimal range of wavelengths of optical radiation was found: from 565 to 615 nm. At these wavelengths, the best results were obtained in terms of seed germination, the length of shoots and roots, as well as the dry weight of the vegetative part and roots. Based on the results obtained, it is possible to formulate the technological requirements for the design and development of a specialized electrotechnical installation using monochromatic optical radiation in agricultural production with the aim of presowing stimulation of seeds of such a vegetable crop as cucumbers.

Grading of Scots Pine Seeds by the Seed Coat Color: How to Optimize the Engineering Parameters of the Mobile Optoelectronic Device

Research Highlights: There is a problem of forest seeds quality assessment and grading afield in minimal costs. The grading quality of each seed coat color class is determined by the degree of its separation with a mobile optoelectronic grader. Background and Objectives: Traditionally, pine seeds are graded in size, but this can lead to a loss of genetic diversity. Seed coat color is individual for each forest seed and is caused to a low error in identifying the genetic features of seedling obtained from it. The principle on which the mobile optoelectronic grader operates is based on the optical signal detection reflected from the single seed. The grader can operate in scientific (spectral band analysis) mode and production (spectral feature grading) mode. When operating in production mode, it is important to determine the optimal engineering parameters of the grader that provide the maximum value of the separation degree of seed-color classes. For this purpose, a run of experiments was conducted on the forest seeds separation using a mobile optoelectronic grader and regression models of the output from factors were obtained. Materials and Methods: Scots pine (Pinus sylvestris L.) seed samples were obtained from cones of the 2019 harvest collected in a natural stand. The study is based on the Design of Experiments theory (DOE) using the Microsoft Excel platform. In each of three replications of each run from the experiment matrix, a mixture of 100 seeds of light, dark and light-dark fraction (n = 300) was used. Results: Interpretation of the obtained regression model of seed separation in the visible wavelength range (650–715 nm) shows that the maximum influence on the output—separation degree—is exerted by the angle of incidence of the detecting optical beam. Next in terms of the influence power on the output are paired interactions: combinations of the wavelength with the angle of incidence and the wavelength with the grader’s seed pipe height. The minimum effect on the output is the wavelength of the detecting optical beam. Conclusions: The use of a mobile optoelectronic grader will eliminate the cost of transporting seeds to and from forest seed centers. To achieve a value of 0.97–1.0 separation degree of Scots pine seeds colored fractions, it is necessary to provide the following optimal engineering parameters of the mobile optoelectronic grader: the wavelength of optical radiation is 700 nm, the angle of incidence of the detecting optical beam is 45° and the grader’s seed pipe height is 0.2 m.

Акустические и акустооптические свойства стекол Ge-=SUB=-a-=/SUB=-Se-=SUB=-b-=/SUB=-Te-=SUB=-c-=/SUB=- и Si-=SUB=-a-=/SUB=-Se-=SUB=-b-=/SUB=-Te-=SUB=-c-=/SUB=- в случае дифракции на продольных и сдвиговых акустических волнах

We investigated acoustic and acousto-optic properties of glasses based on germanium, selenium, silicon and tellurium. The results of measurement are presented for two group of glasses including germanium, selenium and tellurium (GeSeTe) and silicon and tellurium (SiTe). The major characteristics of glasses such as the velocity of longitudinal and shear acoustic waves as well as the values of figure of merit are presented. The values of figure of merit are obtained by diffraction on longitudinal and shear acoustic waves at the wavelength of optical radiation λ = 3.39 µm. We also present the results of measurements of acoustic attenuation values α for longitudinal and shear acoustic waves in tellurium glasses at ultrasound frequencies in the range f = 75-100 MHz.

Investigation of the spectral characteristics of silicon photomultiplier tubes

Успехи прикладной физики, 2021, том 9, No 2165I. R. Gulakov, A. O. Zenevich, and O. V. KocherginaBelarusian State Academy of Communications8/2 F. Skorina st., Minsk, 220114, BelarusE-mail: o.kochergina@bsac.byReceived January 12, 2021Recently multipixel avalanche photodetectors, called silicon photomultipliers are of-ten used to record optical radiation. The influence of ambient temperature and sup-ply voltage on the spectral sensitivity and dynamic range of prototypes of silicon pho-tomultipliers manufactured by JSC "Integral" (Republic ofBelarus) and commercially available photomultipliers KetekRM 3325 and ON Semi FC 30035 has been investigated in this article. It was determined that the spectral sensitivity maxi-mum of silicon photomultipliers is shifted to the short-wavelength region andcorre-sponds to the wavelength of optical radiation of 470 nm. It is shown that an increase in the supply voltage leads to an increase in the sensitivity of the investigated photodetectors, and the dependence of the sensitivity on temperature manifests itself in different ways when exposed to optical radiation of different wavelengths.

High-Precision Apparatus for Measurement of the Cut-Off Wavelength of Single-Mode Optical Fiber

Problems that arise in the course of attempting to determine and monitor an optical fiber, the medium of transmission of fiber-optic communication systems, are considered. One of the controllable parameters is the cut-off wavelength of a single-mode optical fiber. The cut-off wavelength defines the minimal wavelength of optical radiation at which an optical fiber supports only a single propagated mode, i.e., it functions in a single-mode regime. The problem of determining the cut-off wavelength of an optical fiber used in fiber-optic communication systems is critical, since in a multi-mode regime of operation of an optical fiber its throughput decreases as a consequence of inter-mode dispersion. Methods of measuring the cut-off wavelength of an optical fiber are considered. A model of a new high-precision apparatus for measurement of the cut-off wavelength of an optical fiber is proposed. The measurements are performed on the basis of the reference bending method described in GOST R MEK 60793-1-44-2013. The precision characteristics of the newly developed apparatus are analyzed and a quantitative assessment of the measurement error is obtained.

Development of the mathematical model of light flux intensity sensor based on the photodiode and operational amplifier

The article describes a method for interpolating the dependence of the photodiode relative spectral sensitivity on the optical radiation wavelength using a special function that provides interpolation of the experimental dependence with any asymmetry coefficient. A new version of the light flux intensity sensor mathematical model based on a photodiode and an operational amplifier using the proposed interpolation technique has been created. It was found that the interpolation error does not exceed 3–6 %, depending on the type of photodiode and the shape of its experimentally obtained spectral characteristic. The processes occurring in the equivalent circuit of the measuring channel based on the operational amplifier are analyzed. The created mathematical model can be applied to optimize the processes in the measuring channel of the light flux intensity. The research results presented in the article can be used in the design and mathematical modeling of light flux intensity sensors for the needs of various fields of science, industry and medicine.

High-precision apparatus for measuring cutoff wavelength of the single-mode optical fiber

Currently, communication systems are widely used, where optical fiber is used as a transmission medium. In turn, decision and control of optical fiber parameters has become needfull, since these parameters have a significant impact on the quality and quantity of transmitted information using fiber-optic communication systems. One of these parameters is cut-off wavelength of the single-mode optical fiber, which determines the minimum wavelength of optical radiation at which the optical fiber supports only one propagated mode, in other words, operates in single-mode. The problem of decision cut-off wavelength of the optical fiber used in fiber-optic communication systems is quite relevant and demand, since when the optical fiber operates in multimode, its throughput decreases due to inter-mode dispersion. The article describes methods for measuring cut-off wavelength of the optical fiber. Variant of a high- precision apparatus for measuring cut-off wavelength of the optical fiber has been proposed and tested. The measurements were performed based on the reference bending technique described in GOST R IEC 60793-1-44-2013. The analysis of the accuracy characteristics of the developed apparatus is made, a quantitative assessment of the measurement error is obtained.

Spectral studies of phthalocyanines

The paper presents the results of research of the optical properties of nickel-phthalocyanines (NiPc) in a wide spectrum range of optical radiation . Phthalocyanines belong to the group of organic semiconductors with a complicated molecular structure. Spectral characteristics of complex refractive index and optical transmission coefficient were determined. The tests were carried out in the range of wavelengths of optical radiation: 300-2500 nm. By means of Surface Plasmon Resonance (SPR) method, tests concerning the possibilities of using nickel phthalocyanines in gaseous sensors of nitrogen dioxide in atmospheres of air and nitrogen were carried out. Full Text: PDF ReferencesP. Górka, St. Kowalski, Investigation of air pollution, Ed. by SUT, Gliwice, Poland, 2000 CrossRef J. Ignac-Nowicka, T, Pustelny, Z. Opilski,E. Maciak,W. Jakubik, M. Urbanczyk, "Examination of thin films of phthalocyanineas in plasmon system for their application in NO2 sensors", Optical Engineering, 42 (10), 2978 (2003) CrossRef T. Pustelny J. Ignac-Nowicka, Z. Opilski, "Optical investigations on layered metalphthalocyanine nanostructures affected by NO2 applying the surface plasmon resonance method", Opt. Appl. 34(4), 563 (2004) DirectLink J. Homola, "Surface Plasmon Resonance Sensors for Detection of Chemical and Biological Species", Chemical Reviews, 108(2), 462 (2008) CrossRef E. Maciak, T. Pustelny, "An optical ammonia (NH3) gas sensing by means of Pd/CuPc interferometric nanostructures based on white light interferometry", Sensor and Actuators, B: Chemical 189, 230 (2013). CrossRef N.B. McKeown, "Phthalocyanine-containing polymers", Journal of Materials Chemistry, 10 (9), 1979 (2000) CrossRef T Pustelny, J. Ignac-Nowicka, B. Jarzabek, A. Burian, "Optical investigations concerning layered metalphthalocyanine nanostructures affected by NO2", Opt. Appl. 34(4), 551 (2004) DirectLink A. Rydosz, E. Maciak,K. Wincza,S. Gruszczynski, "Microwave-based sensors with phthalocyanine films for acetone, ethanol and methanol detection", Sensors and Actuators, B: Chemical. 237, 876 (2016) CrossRef T. Pustelny, J. Ignac-Nowicka, Z. Opilski, "Experimental investigation of thin metalphthalocyanine layers CuPc, PbPc, NiPc by plasmon resonance method to be applied in NO2-sensors", Opt. Appl. 34(2), 249 (2004) DirectLink W. Jakubik, M. Urbanczyk, E. Maciak, T. , "Surface acoustic wave hydrogen gas sensor based on layered structure of palladium/metal-free phthalocyanine", Bull. Pol. Acad. Sci.-Tech. Sci., 56(2), 133 (2008) DirectLink M. Piliaric, J. Homola, "SPR Sensor Instrumentation", Chemical Sensors and Biosensors, 4, 95 (2006) CrossRef

AMPLITUDE CHARACTERISTICS OF SILICON PHOTO-ELECTRON MULTIPLIER’S PHOTORESPORENSE

Currently, in many applications, photodetectors are needed that provide registration of optical radiation in a wide range of intensities and allow combining two operating modes: current mode and photon counting. These devices include silicon photoelectronic multipliers (SiPM), which have a number of advantages compared to electrovacuum photomultipliers and avalanche photodetectors. However, the influence on the photoresponse characteristics of SiPM of such important factors as the supply voltage and temperature has not been studied enough. The influence of these factors on the amplitude parameters of the photoresponse of SiPM is studied. The block diagram of the experimental setup is presented, with the help of which the photoresponse characteristics of SiPM with n+-n-p+ and p+-p-n+ structures manufactured by Integral OJSC (Republic of Belarus) were measured. The dependences of the average amplitude of the photoresponse on the supply voltage and temperature of silicon photomultipliers for various wave-lengths of optical radiation are presented. It was found that when SiPM were exposed to optical pulses with the same duration and energy exposure at the same temperature at the same overvoltage, the photoresponse amplitude was larger for a SiPMr with p+-p-n+ structure regardless of the wave-length of optical radiation. It was found that, when the overvoltage changes, the increase in the photoresponse amplitude is observed only in the overvoltage range ΔU = 0 ¸ 3 V for all the studied SiPM, irrespective of the wave-length of the detected optical radiation and temperature. It was determined that a decrease in temperature led to an increase in the amplitude of the photoresponse pulses. The temperature dependence of the amplitude of the photoresponse was most pronounced for SiPM with the p+-p-n+ structure. It was shown that the dependences of the average amplitude of the photomonitor Si-PM on the energy exposure have a linear section, the length of which depends on the wavelength of the detected optical radiation.

Фоточувствительность оптических сенсоров на основе дихалькогенидов переходных металлов: влияние толщины на их спектральные характеристики

In this work, samples of field-effect transistors were fabricated based on solid solutions of transition metal dichalcogenides and their spectral characteristics were studied using photocurrent spectroscopy. The results of a theoretical estimate of the total optical absorption of two-dimensional semiconductors at different thicknesses of the sample and for different wavelengths of optical radiation with allowance for multibeam interference are presented. It is shown that interference effects make a significant contribution to the change in the shape of the spectral characteristics of optical sensors with a change in the thickness of the photosensitive layer of transition metal dichalcogenides.

Magnetic field-driven lateral photovoltaic effect in the Fe/SiO2/p-Si hybrid structure with the Schottky barrier

We demonstrate that the lateral photovoltaic effect in the Fe/SiO2/p-Si structure not only strongly depends on the optical radiation wavelength and temperature, but is also sensitive to external magnetic fields. The magnetic field lowers the absolute value of photovoltage regardless of the wavelength and temperature; however, the relative photovoltage variation significantly depends on these parameters. The lateral photovoltage is observed both on the Fe film and Si substrate sides and results from separation of photoinduced electrons and holes in a built-in electric field of the Schottky barrier with their subsequent diffusion to the structure in the lateral direction from the illuminated area. The observed features in the behavior of the lateral photovoltaic effect originate from the variation in the light absorption coefficient of the semiconductor and the related quantum efficiency upon light wavelength variation. In addition, an important role is played by the change in the characteristics of the Schottky barrier at the redistribution of optically generated carriers and temperature variation. The effect of the magnetic field is attributed to the Lorentz force, which bends trajectories of carriers drifting under the action of the Schottky barrier field and, consequently, suppresses the lateral photovoltaic effect.